1. Field of the Invention
The present invention relates to liquid crystal dropping apparatus and method, and a liquid crystal display panel producing apparatus.
2. Description of the Related Art
Generally, a liquid crystal display panel producing apparatus inserts liquid crystal between a lower substrate and an upper substrate and bonds the lower substrate and the upper substrate. The liquid crystal display panel producing apparatus comprises a sealing agent drawing apparatus for drawing a sealing agent with a closed pattern along an outer edge of the lower substrate, a liquid crystal dropping apparatus for dropping the liquid crystal on a planned drop region surrounded by the sealing agent of the lower substrate, a substrate bonding apparatus for bonding the lower substrate to the upper substrate under a reduced pressure so that air bubbles do not remain in the liquid crystal, and a sealing agent hardening apparatus to harden the sealing agent interposed between the upper substrate and the lower substrate.
As a conventional liquid crystal dropping apparatus, as described in Japanese Patent Applications Laid-open No. H10-221666 and No. 2001-330840, there is proposed an apparatus in which liquid crystal discharged from a plurality of discharging ports of ink-jet type liquid crystal dropping head is allowed to drop on the planned drop region on the lower substrate.
In the conventional liquid crystal dropping apparatus, the liquid crystal is discharged from all of the discharging ports of the liquid crystal dropping head, and there are problems as follows:
1) When an entire dropping subject width W of the planned drop region based on a substrate size has a relation of (W=n×L+α (n is an integer, α<L)) with respect to an entire discharging width L of the liquid crystal from all the discharging ports of the liquid crystal dropping head, a liquid crystal band-like body of at least a width L which is dropped at the time of the last scanning of the liquid crystal dropping head which is scanned on the planned drop region in a form of a U-turn shape is superposed on a portion of the width of the liquid crystal band-like body of a width L on which the liquid crystal is dropped at the time of the last scanning but one. Therefore, the liquid crystal can not be dispersed uniformly over the entire region of the planned drop region on the substrate, which deteriorates the display precision of the liquid crystal.
2) Since a constant amount of liquid crystal is discharged from all of the discharging ports of the liquid crystal dropping head, it is not possible to control the dropping amount of the liquid crystal with respect to the planned drop region. Therefore, when the lower substrate and the upper substrate are bonded to each other, it is difficult to prevent the liquid crystal from overflowing from the sealing agent and to prevent a sealing failure from being generated, because it is difficult that the dropping amount of the liquid crystal in a region along the sealing agent is reduced with respect to the dropping amount of the liquid crystal in a central region on the lower substrate.